Method of making a thermally insulated polyurethane shipper

ABSTRACT

A method of making a thermally insulated sandwich polyurethane (PUR) shipper for a temperature sensitive payload is provided. The method comprises the steps of mounting an inner box upside down on a tool, adhering an insulating panel to the outer facing surfaces of the inner box, positioning an outer box around the inner box assembly, pouring liquid polyurethane into the gap between the outer box and inner box assembly, and foaming the liquid polyurethane. The PUR foam fills the space between the VIP panels and the outer box, and preferably covers the VIP panels.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/919,561, filed on Jun. 17, 2013.

FIELD OF THE INVENTION

This invention relates to a thermally insulated sandwich polyurethane(PUR) shipper for shipping temperature sensitive payloads. Moreparticularly, this invention relates to a thermally insulated sandwichPUR shipper for shipping temperature sensitive payloads that avoids thedisadvantages of other insulated containers while affording additionalstructural and operating advantages.

DESCRIPTION OF THE RELATED ART

Thermally insulated shippers are used to ship perishable materials suchas pharmaceuticals, blood and blood products, transplant organs and foodproducts which must be maintained within a certain temperature range.The shipping and transportation of various perishable materialsfrequently requires that such materials be maintained in a stabletemperature range either higher or lower than the ambient temperaturesto which the packaging will be exposed. A number of different types ofthermally insulated containers have been developed for this purpose.They generally fall into two main categories, active shippers andpassive shippers.

Active shippers are those in which the internal temperature iscontrolled using a battery operated device or electrical power cord.These systems usually are expensive and quite bulky.

Passive shippers are those in which the internal temperature ismaintained without any battery or electrical support. Differentmaterials may be used to control the temperature, such as phase changematerial (material which can absorb or release heat depending on thesurrounding temperature), gel bricks (a.k.a. ice bricks), vacuuminsulation panels and dry ice.

There are at least three types of passive shippers:

1. EPS shippers. EPS shippers are made out of expanded polystyrene foam(EPS) and may use a combination of other components such as a corrugatedbox, vacuum insulation panels, phase change materials, gel bricks anddry ice. Expanded foam shippers can also be made out of other types ofexpanded foam including but not limited to expanded polypropylene (EPP),expanded polystyrene (EPS) and expanded polyethylene (EPE).

2. Vacuum Insulated Panel (VIP) shippers. A vacuum insulated panel is aproduct composed of a rigid, highly-porous nano size material core madefrom fused silica, aerogel, or glass fiber that is surrounded by ametalized or non-metallized plastic film enclosure that is vacuum packedand nearly hermetically sealed so as to remove any remnant air particleswithin the enclosure. The principal reason why VIP panels are highlysought after as material for use in insulation is due to theirexceptionally high thermally insulating properties. For example, EPS andpolyurethane, which are typical insulating materials, have an R-value ofabout 4 to 4.5 and 5 to 6 hr-ft²-° F./BTU-in respectively, whereas theR-value for a VIP panel of the same thickness is typically 35-40hr-ft²-° F./BTU-in or more. In order for EPS or polyurethane to be aseffective as a VIP panel, the same EPS or polyurethane sheets would needto be made about seven or eight times thicker. An open topped box of VIPpanels can be made from five individual panels taped together usingpackaging tape or strapped together using band straps.

3. Polyurethane (PUR) shippers. PUR shippers are made by adding a liquidPUR mix (a mixture of isocyanate, polyol, catalysts, blowing agents)into a corrugated box and then curing (foaming) the liquid to create PURfoam. The PUR foam can be made in different densities and hardnesses.

The use of most if not all of these passive shippers involves a numberof challenges:

Edge Leaks in VIP Shippers

A typical VIP shipper is made by assembling five individual VIP panelsand securing the panels together using packaging tape or strapping themtogether using band strap. Despite the care given to assembly, there canbe significant air gaps (edge leaks) formed between the VIP panelsduring the assembly. These gaps are difficult to eliminate due to theoften uneven shape of the VIP panels around the edges. Even thoughindividual VIP panels may have an R-value of up to 40/inch, the overallshipper R-value may be anywhere between 25 to 30, a 25-30% drop. Thedrop in R-value is due to the edge leaks. This is also one of the mainreasons packaging system consisting essentially of VIP panels are havingdifficulty being successful in the insulated shipper market. They areexpensive, and their insulative benefits are greatly compromised due toedge leaks.

Edge leaks in general occur when two adjoining walls of material are notcompletely in contact/flush with one and another and therefore create avisible gap, also known as a thermal bridge. This thermal bridge createsa path of least resistance for heat to transfer through, thus makingeven high R-value materials ineffective at preventing thermaltransmissions. The R-value of the entire system is compromised andlanguishes to levels of systems with no VIP panels. Simply addingadditional thermal insulation to the enclosure is of little benefit; thethermal bridge must be minimized or eliminated completely in order forthe system's R-value to be substantially enhanced.

The majority of air leaks arise in circumstances where manual labor isused to assemble the final product and where the mating surfaces of thecomponents being connected together are irregularly shaped or highlyunrefined. (Edge gaps can significantly widen during the standardtransportation resulting in further reduction of shipper R-value.)Because the edge leaks are predominantly a function of the productioncontrol process of the particular product being manufactured, it isgreatly desired that the manufacturing operations have as tight controlas possible of the tolerances and procedures as cost allows. This inturn means that all manual operations should ideally be eliminated orcontrolled in such a way that the assembler's own experience does notweight heavily upon the final quality of the product.

Knife Defects, Puncture Defects in VIP Shippers

Vacuum (lack of gas molecules) is the primary reason why the R-values ofVIP panels are so high. The outside casing of these panels is made up offlexible plastic film. The R-value of a VIP panel without a vacuum isabout 4/inch and this similar to EPS. If a VIP panel gets damaged due topuncturing or rough handling then the R-value drops due to the loss ofthe vacuum. The R-value will also drop over time because the flexibleplastic film is not completely impermeable to gas and moisture. However,the most common defect in shipping containers that comprise VIP panelsis the compromise of the flexible plastic film due to punctures ortears. VIP shippers typically are enclosed in a cardboard box. Extracare needs to be taken during unpacking and opening the box. A knifeblade can easily puncture the flexible plastic film resulting in asignificant drop in the R-value from 40 to 4/inch. The entire shipperwill fail even if the failure is just in one VIP panel.

Manual Labor Requirements in VIP Shippers

As briefly mentioned above, the method currently used to create VIPboxes demands heavily upon manual manipulation, an inexact operation,where the individual panels are joined by the individual to hold theindividual panels temporarily into place while wrapping and attachingadhesive bindings such as tape or straps to compress the panelstogether, a requirement that is dictated by the need to minimize edgeleaks. Because there currently are no technologies to instantlydetermine what the operating R-value is of the final package, or even ina relatively short period of time, there is no reliable method to ensurethe thermal quality of the final product. Due to such shortcomings, amore repeatable and controlled method is desired.

Transportation Considerations in VIP Shippers

Transportation and the resulting vibrations that occur duringtransporting are important factors to consider when selectingappropriate packaging needs. With current manually produced VIP panelpackages, the risk of compromising the R-value properties of the packageis high, especially when the package undergoes severe shock or changesin momentum, such as when falling or wildly translating about a shelf ona vehicle. Manually constructed VIP packages that are held together withadhesive tape or another binding system that was never designed toabsorb impact or loads of any kind present a particular challenge.Excessive vibration or impacting of a package with a large enoughamplitude during transportation can and often does create edge leakagedue to air gaps between the VIP panels that deleteriously affects theperformance of such packaging systems. Requiring couriers to be moregentle or use greater care when handling the package is usually beyondthe control of the package maker or user. By designing a package tocreate a more robust and sturdy structure, the problems associated withtransportation and vibration can be mitigated or even eliminated.

PUR shippers are widely used in the pharmaceutical and medicalindustries to ship drugs and medical related products all over theworld. The primary advantage of a PUR shipper over an EPS shipper is thehigher insulation (R) value. Insulating properties of PUR (R-value of6/inch) are 50% better than EPS (R-value of 4/inch).

Standard PUR shippers used in the pharmaceutical and medical shippingindustries are made with 2-3″ of wall thickness. Depending on the sizeof payload and type of refrigerants used inside the box, PUR shippersare bulky and the total weight of the shipper (including payload andrefrigerants) can easily reach 40-50 lbs. Size and weight are twoprimary factors impacting the cost in a shipping industry. The presentinvention is designed to solve the problems described above.

BRIEF SUMMARY OF THE INVENTION

The present invention is an improved thermally insulated sandwich PURshipper which avoids the disadvantages of prior insulated containerswhile affording additional structural and operating advantages. Thepresent invention is also a method of making an improved thermallyinsulated sandwich PUR shipper.

In one aspect the invention is a packaging system for shipping atemperature sensitive payload, the packaging system comprising an outercorrugated box, an inner corrugated box, insulating panels and PUR foam.The inner box is nested within the outer box and has a bottom, sides anda top. The inner box defines a payload compartment. The bottom and sidesof the inner box have outer facing surfaces facing away from the payloadcompartment. The insulating panels are adhered to the outer facingsurfaces of the inner box. The PUR foam fills the space between theinsulating panels and the outer box. Preferably the insulating panelsare wedged against each other so that a side edge of one insulatingpanel abuts an adjacent insulating panel. The PUR foam may cover the topedges of the insulating panels.

The insulating panels may be VIP panels or any other suitable panel madeof insulation material (instead of VIP) with insulation values(R-values) equal to or greater than the PUR foam. In some instances theR-values of the insulation panels may be twice that of the PUR foam oreven higher.

In another aspect of the invention a method of making a sandwich PURshipper is provided. The method may comprise the steps of:

Step 100: Providing an inner box having a bottom and four sides. Thisstep may include mounting the inner box upside down on a tool.

Step 102: Adhering an insulating panel such as a VIP panel to the outerfacing surface of at least one of the inner box bottom and sides tocreate an inner box assembly.

Step 104: Positioning an outer box around the inner box assembly so thatthere is a gap between the outer box and the inner box assembly. If themethod is being performed using a tool, this step may include using thetool to hold the outer box steady so that it does not contact the innerbox assembly.

Step 108: Pouring liquid polyurethane into the gap.

Step 110: Foaming the liquid polyurethane. This step may includecovering the insulating panels with PUR foam.

In a tool is used, after Step 104 and before Step 108 the method maycomprise the further step of:

Step 106: Inverting the tool 180 degrees so that the nested boxes arenow right side up.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a thermally insulated sandwich PURshipper according to the invention.

FIG. 2 is a perspective view of an outer corrugated box used in makingthe thermally insulated sandwich PUR shipper of FIG. 1.

FIG. 3 is a perspective view of an inner box used as a component of thesandwich PUR shipper 10 of FIG. 1.

FIG. 4 is a perspective view of a VIP panel used as a component of thesandwich PUR shipper 10 of FIG. 1.

FIG. 5 is a perspective view of part of a tool that may be used to makethe thermally insulated sandwich PUR shipper of FIG. 1.

FIG. 6 is a schematic diagram showing a method of making the thermallyinsulated sandwich PUR shipper of FIG. 1.

FIG. 7 is a perspective view of an outer corrugated box mounted on topof an inner box assembly.

FIG. 8 is a perspective view of an operator pouring liquid polyurethaneinto the air gap between the outer box and the inner box.

FIG. 9 is a perspective view of an operator closing the tool and foamingthe PUR.

FIG. 10 is a top perspective view of a completed sandwich PUR shippershown with some of the PUR foam removed for clarity.

FIG. 11 is a graph comparing the thermal performance of a sandwich PURshipper according to the disclosure to a PUR shipper for a summerambient profile.

FIG. 12 is a graph comparing the thermal performance of a sandwich PURshipper according to the disclosure to a PUR shipper for a winterambient profile.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many forms, there is shown inthe drawings and will herein be described in detail one or moreembodiments with the understanding that this disclosure is to beconsidered an exemplification of the principles of the invention and isnot intended to limit the invention to the illustrated embodiments. Forinstance, while the sandwich PUR shipper of the disclosure will now bedescribed as comprising VIP panels, it should be understood that theinsulating panels can be any suitable insulating panel.

The term R-value as used herein refers to the resistance of a materialto heat flow, and typically is expressed in units of hr-ft²-° F./BTU-in,referring to the thermal resistance of a material that is a nominal oneinch thick. Where units are not explicitly provided, the R-value shouldbe understood to be in units of hr-ft²-° F./BTU-in.

The Thermally Insulated Sandwich PUR Shipper

The invention is a thermally insulated sandwich polyurethane (PUR)shipper for shipping a temperature sensitive payload and a method ofmaking the same.

Turning to the drawings, FIG. 1 is a perspective view of a sandwich PURshipper 10 according to one aspect of the invention. The sandwich PURshipper 10 comprises an outer box 12, an inner box 14 nested within theouter box 12, insulating panels such as vacuum insulated panels (VIPpanels) 16 adhered to the exterior sides and bottom (outer facingsurfaces) of the inner box 12, and PUR foam 18 located between the VIPpanels 16 and the outer box 18. The top 32 of the inner box 14 has beenremoved for clarity.

The insulating panels may be VIP panels or any other suitable panel madeof insulation material (instead of VIP), preferably with an insulationvalue (R-value) equal to or greater than the PUR foam. In some instancesthe R-value of the insulation panels may be about twice that of the PURfoam or even higher. For example, VIP panels may have an R-value ofabout 35 to 40, much higher than the typical R-value of 5 to 6 for PURfoam.

FIG. 2 is a perspective view of an outer box 12 used as a component ofthe sandwich PUR shipper 10 of FIG. 1. Preferably the outer box 12 ismade of corrugated material and comprises bottom flaps 22 that form thebottom 22 of the outer box 12, four side panels 24 extending from theperiphery 23 of the bottom 22 to the top periphery 27, and a top 26comprised of top flaps 26 foldably attached to the side panels 24 alongthe top periphery 27.

FIG. 3 is a perspective view of an inner box 14 used as a component ofthe sandwich PUR shipper 10 of FIG. 1. Preferably the inner box 14 ismade of corrugated material and comprises a bottom 28 having a bottomperiphery 29, four side panels 30 extending from the periphery 29 of thebottom 28 to a top periphery 33, and a top 32 comprised of top flaps 32foldably attached to the side panels 30 along a top periphery 33. Thetop flaps 32 may be folded together to close the inner box 14. The innerbox 14 may be sealed with tape 37 or other suitable means.

The inner box 14 is smaller than the outer box 12 so that the inner box14 can nest within the outer box 12, leaving a gap therebetween foraccommodating the VIP panels 16 and the PUR foam 18. The inner box 14defines an interior space 20 (FIG. 1) for holding a payload.

The VIP panels 16 may generally be composed of a rigid, highly-porous,nano-size material core made from fused silica, aerogel, or glass fiber,surrounded by a plastic film enclosure that is vacuum packed and nearlyhermetically sealed so as to remove any remnant air particles within theenclosure. As shown in FIG. 4, each VIP panel 16 is generallyrectilinear in shape, somewhat like a flattended brick, with two flatsides 35, three substantially flat side edges 34 and a substantiallyflat top edge 36. Each vacuum insulated panel 16 may be orientedsubstantially orthogonally to at least one adjacent vacuum insulatedpanel 16 and have one or more edges 34 that abut the adjacent vacuuminsulated panels 16.

Referring back to FIG. 1, the VIP panels 16 are located between thenested outer box 12 and inner box 14 and, more specifically, between thePUR foam 18 and the inner box 14, which protects the VIP panels 16 frompunctures or tearing. Preferably the VIP panels 16 are wedged againsteach other together so that the side edge 34 of one VIP panel 16 abutsan adjacent VIP panel 16, thereby reducing or eliminating edge leaks.The PUR foam 18 may cover the top edges 36 of the VIP panels 16 to sealoff the VIP panels 16 so they are completely enclosed as shown in FIG.10.

Method of Making the Sandwich PUR Shipper

The sandwich PUR shipper may be made using a tool 40 such as that shownin FIG. 5. FIG. 6 is a schematic diagram showing a method of making thethermally insulated sandwich PUR shipper 10 of FIG. 1. The method maycomprise the following steps:

Step 100: Mounting an inner box 14 upside down on a tool 40.

Step 102: Adhering an insulating panel 16 such as a VIP panel 16 to theexterior (outer box facing) side of each of the inner box bottom 28 andsides 30 using a sealant or other suitable means to create an inner boxassembly 38 such as that shown in FIG. 5. There should be no VIP panel16 adhered to the top 32 of the inner box 14.

Step 104: Mounting an outer box 12 on top of the inner box assembly 38as shown in FIG. 7 so that there is a gap 50 (space) between the outerbox 12 and the VIP panels 16 or inner box assembly 38. The tool 40should hold the outer box 12 steady so that it does not contact theinner box assembly 38. The inner box assembly 38 is obscured by theouter box 12 in FIG. 7 but may be seen partially in FIGS. 8 and 10.

Step 106: Closing the bottom flaps 22 of the outer box 12 and invertingthe tool 180 degrees so that the nested boxes 12, 14 are now right sideup as shown in FIG. 8. The inner box assembly 38, including the innerbox 14 and the VIP panels 16 adhered to the sides 30 of the inner box14, can be seen in FIG. 8 nested within the outer box 12. The outer box12 is shown with its top flaps 26 open. An operator O is shown in theright foreground.

Step 108: Pouring liquid polyurethane into the air gap 50 between theouter box 12 and the VIP panels 16 as shown in FIG. 8. The PUR willsettle around the bottom of the outer box 12. The volume of PUR may beabout 10% of the volume of the air gap 50.

Step 110: Closing the tool 40 and foaming the PUR for about 15-30minutes as shown in FIG. 9. The PUR foam 18 should fill the entire gap50 between the outer box 12 and the VIP panels 16.

FIG. 10 is a top perspective view of a completed sandwich PUR shipper 10shown with some of the PUR foam 18 removed for clarity. Preferably, thePUR foam 18 covers the VIP panels 16 to seal off the VIP panels 16 sothey are completely enclosed as shown in FIG. 10.

The resulting shipper 10 uses less PUR than conventional shippers andmay have improved performance over some conventional PUR shippers.

Case Studies

The following case studies compare performance between a sandwich PURshipper according to the disclosure and a standard PUR shipper undersummer conditions and winter conditions.

Case Study 1—Summer Ambient Profile

In case study 1, the performance of a sandwich PUR shipper was comparedto the performance of a standard PUR shipper of identical size. Theobjective was to maintain the specification pay load (eg. vaccines)between 2-8 degrees C. for a period of 72 hours.

FIG. 11 is a graph comparing the thermal performance of the sandwich PURshipper according to the disclosure to the standard PUR shipper for asummer ambient profile. The sandwich PUR shipper passed the summerambient profile test while standard PUR shipper failed after 36 hours.

Case Study 2—Winter Ambient Profile

In case study 2, the performance of a sandwich PUR shipper was comparedto the performance of a standard PUR shipper during a winter ambientprofile. Again, the objective was to maintain the pay load between 2-8degrees C. for a period of 72 hours.

FIG. 12 is a graph comparing the thermal performance of the sandwich PURshipper according to the disclosure to the PUR shipper for a winterambient profile. The sandwich PUR shipper maintained product temperaturewithin a narrow tolerance while the standard PUR shipper failed tomaintain product within the specified temperature range.

Both case studies 1 and 2 confirm that a sandwich PUR shipper accordingto the present disclosure can exceed the performance of a standard PURshipper. The sandwich PUR shipper is capable of meeting a producttemperature range specification (eg., 2-8 degrees C.) irrespective ofsummer or winter ambient profile.

Case Study 3—Reduction in Size and Weight

The following table compares volume and size reduction achieved byconstructing a sandwich PUR shipper according to the present disclosure.

TABLE 1 Shipper Type Outer Dimensions, Inches Sandwich PUR Shipper17.28″ × 11.03″ × 12.78″ Standard PUR Shipper 20.05″ × 14.25″ × 16″

While keeping the insulation value of the overall shipper the same, asandwich PUR shipper can achieve a 47% reduction in volume and up to a20% reduction in weight.

INDUSTRIAL APPLICABILITY

The thermally insulated sandwich PUR shipper may be used in any industrywhere temperature sensitive products are shipped, including but notlimited to the pharmaceutical, hospital and food industries.

It is understood that the embodiments of the invention described aboveare only particular examples which serve to illustrate the principles ofthe invention. Modifications and alternative embodiments of theinvention are contemplated which do not depart from the scope of theinvention as defined by the foregoing teachings and appended claims. Itis intended that the claims cover all such modifications and alternativeembodiments that fall within their scope.

The invention claimed is:
 1. A method of making a sandwich PUR shippercomprising the steps of: Step 100: Providing an inner box having abottom and four sides; Step 102: Adhering an insulating panel to theouter facing surface of each of the inner box sides to create an innerbox assembly, each insulating panel having a top edge that faces awayfrom the inner box bottom; Step 104: Positioning an outer box on top ofthe inner box assembly so that the inner box and outer box are nestedand so that there is a gap between the outer box and the inner boxassembly; Step 108: Pouring liquid polyurethane into the gap; and Step110: Foaming the liquid polyurethane to create PUR foam that covers thetop edge of each insulating panel so that the insulating panels arecompletely enclosed by the inner box and the PUR foam.
 2. The method ofclaim 1 wherein: Step 100 includes mounting the inner box upside down ona tool; and Step 104 includes using the tool to hold the outer boxsteady so that it does not contact the inner box assembly.
 3. The methodof claim 2 wherein, after Step 104 and before Step 108, the methodcomprises the further step of: Step 106: Inverting the tool 180 degreesso that the nested boxes are right side up.
 4. The method of claim 2wherein: each insulating panel is generally rectilinear in shape.
 5. Themethod of claim 1 wherein: the PUR foam has an R-value; and theinsulating panels have an R-value equal to or greater than the R-valueof the PUR foam.
 6. The method of claim 5 wherein: the insulating panelshave an R-value greater than that of the PUR foam.
 7. The method ofclaim 6 wherein: the insulating panels have an R-value about at leasttwice that of the PUR foam.
 8. The method of claim 1 wherein: theinsulating panels are VIP panels.
 9. The method of claim 1 wherein: Step102 includes wedging the insulating panels against each other so that aside edge of each insulating panel abuts an adjacent insulating panel.10. A method of making a sandwich PUR shipper comprising the steps of:Step 100: Providing an inner box having a bottom and four sides; Step102: Adhering an insulating panel to the outer facing surface of each ofthe inner box bottom and sides to create an inner box assembly, eachinsulating panel having a top edge that faces away from the inner boxbottom; Step 104: Positioning an outer box on top of the inner boxassembly so that the inner box and outer box are nested and so thatthere is a gap between the outer box and the insulating panels; Step108: Pouring liquid polyurethane into the gap; and Step 110: Foaming theliquid polyurethane to create PUR foam that fills the entire gap betweenthe outer box and the insulating panels and covers the top edge of eachinsulating panel.
 11. The method of claim 10 wherein: Step 100 includesmounting the inner box upside down on a tool; and Step 104 includesusing the tool to hold the outer box steady so that it does not contactthe inner box assembly.
 12. The method of claim 11 wherein, after Step104 and before Step 108, the method comprises the further step of: Step106: Inverting the tool 180 degrees so that the nested boxes are rightside up.
 13. The method of claim 10 wherein: the PUR foam has anR-value; and the insulating panels have an R-value equal to or greaterthan the R-value of the PUR foam.
 14. The method of claim 13 wherein:the insulating panels have an R-value about at least twice the R-valueof the PUR foam.
 15. The method of claim 10 wherein: Step 102 includeswedging the insulating panels against each other so that a side edge ofeach insulating panel abuts an adjacent insulating panel.
 16. The methodof claim 10 wherein: Step 102 includes adhering a bottom insulatingpanel to the outer facing surface of the inner box bottom.
 17. Themethod of claim 16 wherein: the insulating panels and the bottominsulating panel are VIP panels.